The parseFloat() is an inbuilt function in JavaScript which is used to accept the string and convert it into a floating point number. If the string does not contain a numeral value or If the first character of the string is not a Number then it returns NaN i.e, not a number. It actually returns a floating point number parsed up to that point where it encounters a character which is not a Number.
Syntax:
parseFloat(Value)
Parameters: It accepts a parameter “value” which contains a string which is converted to a floating point number.
Return value: It returns a floating point Number and if the first character of a string cannot be converted to a number then the function returns NaN i.e, not a number.
Example:
Input: var n = parseFloat(" 2018 "); Output: n=2018 (floating point Number) The parseFloat() function ignores leading and trailing spaces and returns the floating point Number of the string. Input: var a = parseFloat("1000.04"); Output: now a = 1000.04(floating point Number)
Code #1:
<!DOCTYPE html> <html> <body> <script> // It ignores leading and trailing spaces. a = parseFloat( " 100 " ) document.write( 'parseFloat(" 100 ") = ' +a + "<br>" ); // It returns floating point Number until // it encounters Not a Number character // It returns NaN on Non numeral character d = parseFloat( "3.14" ) document.write( 'parseFloat("3.14") = ' +d + "<br>" ); // It returns only first Number it encounters e = parseFloat( "22 7 2018" ) document.write( 'parseFloat("22 7 2018") = ' +e + "<br>" ); </script> </body> </html> |
Output:
parseFloat(" 100 ") = 100 parseFloat("[email protected]") = 2018 parseFloat("[email protected]") = NaN parseFloat("3.14") = 3.14 parseFloat("22 7 2018") = 22
Code #2:
Using isNaN() function to test that converted values are valid number or not.
<!DOCTYPE html> <html> <body> <script> var x = parseFloat( "3.14" ); if (isNaN(x)) document.write( "x is not a number" + "<br>" ); else document.write( "x is a number" + "<br>" ); var y = parseFloat( "geeksforgeeks" ); if (isNaN(y)) document.write( "y is not a number" + "<br>" ); else document.write( "y is a number" + "<br>" ); // Difference between parseInt() and parseFloat() var v1 = parseInt( "3.14" ); var v2 = parseFloat( "3.14" ); document.write( 'Using parseInt("3.14") = ' + v1 + "<br>" ); document.write( 'Using parseFloat("3.14") = ' + v2 + "<br>" ); </script> </body> </html> |
Output:
x is a number y is not a number Using parseInt("3.14") = 3 Using parseFloat("3.14") = 3.14
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